Paradise Biryani — higher prices through 3rd party apps

Paradise biryani is selling their items at higher price in 3rd party apps like zomato and foodpanda. I recently purchase chicken biryani family pack in one of the paradise outlet near hi-tech city, hyderabad with a charge of 529+gst. The same biryani from the same hotel is showing as 609+gst on apps like zomato and foodpanda.

When i inquired zomato about it, i received a confirmation that it is paradise who decides the prices.

What kind of business ethics it is? Whose responsibility it is to inform customers in advance about such high prices? Why can't the apps like zomato and foodpanda shows the original price and price in their app and let customers decide whether they want to order through the app or not?